Mueller is that so that there is no investigation of the perpetrators of Spygate and the continuing coup attempt against the President of the United States.
Yes, they buy time to let the crimes under the Obama administration fade.
First they screamed “Russia! Russia! Russia!”.....
Personally, I think this aspect isn't talked about quite as much as it should be.
Part of what Trump campaigned on was "Lock her up!"
And although after the election Trump almost immediately took a magnanimous attitude and indicated that he didn't feel the need to actually prosecute Hillary and her friends, the Democrats nevertheless brought out all the big legal guns and have tied Trump up in the courts for over two years. It becomes quite awkward to have lawyers pursuing Democrat malfeasance because, now, it just looks like childish payback on Trump's part.
As a purely defensive maneuver, the legal offensive against Trump has worked well for the Democrats.